The present invention relates generally to semiconductor devices and more specifically to methods of fabricating improved bonding pads.
Low-k materials have poor mechanical strength and cause serious concerns in conjunction with wire bonding to wire bonding pads. Also, the low-k material exhibits some problems of low adhesion and bad heat transport. These problems are most significant on the top, or upper wire bonding pad, which is susceptible to the highest stress during wire bonding compared to lower, or underlying layers.
U.S. Pat. No. 5,783,868 to Galloway describes the fabrication and use of a bonding pad extension for the purposes of burn-in testing. The extension is used only for connections during such testing and is preferably formed to be easily removed after the burn-in testing.
U.S. Pat. No. 6,028,367 to Yu describes a bond pad structure equipped with a heat dissipating ring surrounding the pad and a method to fabricate the structure.
U.S. Pat. No. 5,942,800 to Yiu et al. describes a chess-board patterned bond pad structure with stress buffered characteristics and a method to fabricate the structure.
U.S Pat. No. 5,923,088 to Shiue et al. describes a bond pad structure with plugs underneath to prevent peeling and a method to fabricate the structure.
U.S. Pat. No. 5,874,356 to Chen et al. describes a method for forming a zig-zag bordered opening in a semiconductor structure such that the film stress in a barrier/glue layer of TiN is reduced to eliminate volcano defects that cause delamination or peeling-off of the TiN layer.
U.S. Pat. No. 6,025,277 to Chen et al. describes a bond pad structure where a hole is etched that is wider in an lower, first insulating layer than in an upper, second insulating layer.
Accordingly, it is an object of the present invention to provide a bonding pad structure having a wire bond affixed to a planar dielectric area having a stronger mechanical strength, and a method to fabricate same.
Another object of the present invention is to provide a method to fabricate a bonding pad structure having a wire bond affixed to a planar dielectric area without causing dielectric cracking or peeling, and a method to fabricate same.
Other objects will appear hereinafter.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner. Specifically, a substrate having a top metal layer and a passivation layer overlying the top metal layer is provided. The top metal layer being electrically connected to a lower metal layer by at least one metal via within a metal via area. The substrate includes a low-k dielectric layer at least between the lower metal layer and the top metal layer. The passivation layer is etched within the metal via area to form a trench exposing at least a portion of the top metal layer. A patterned, extended bonding pad is formed over the etched passivation layer and lining the trench. The extended bonding pad having a portion that extends over a peripheral planar area of the substrate adjacent the trench not within the metal via area. A wire bond is bonded to the extended bonding pad at the peripheral planar area portion to form the bonding pad structure.